1. Field of the Invention
The present invention relates in general to an emission control device of an internal combustion engine, and more particularly to a crankcase emission control device that positively routes blow-by gases from the crankcase to the intake system of the engine. More specifically, the present invention relates to the crankcase emission control devices of a type that positively routes blow-by gases from the crankcase to the intake system through a valve rocker cover chamber of the cylinder head and a gas/liquid separator defined by the cylinder head.
2. Description of the Related Art
Hitherto, various crankcase emission control devices have been proposed and put into practical use in the field of internal combustion engines that are mounted in wheeled motor vehicles. Almost all them are of a type wherein by introducing fresh air into the crankcase, blow-by gases in the crankcase are enforcedly led to the intake system and to the cylinder combustion chambers together with the air-fuel mixture to be burnt. Usually, the crankcase emission control device is equipped at a blow-by gas flowing passage thereof with an oil separator, viz., gas/liquid separator for suppressing migration of a lubrication oil together with the blow-by gases from the crankcase. One of the crankcase emission control devices with such gas/liquid separator is disclosed in Japanese Laid-open Patent Application (Tokkai) 2003-001030. In this disclosed device, the gas/liquid separator is integrally provided on an inner surface of a cylinder head cover that covers an open upper part of the cylinder head.